Tire pressure controlling apparatus



May 2, 1939. w DAVls 2,156,841

TIRE PRESSURE CONTROLLING APPARATUS Filed April 9, 1958 3 SheetsSheet lu; I, M44 751? ix DAV/rs attorneys May 2, 1939. w. H. DAVIS TIREPRESSURE CONTROLLING APPARATUS Filed' April 9, 193a s Sheets-Sheet 2 May2, 1939.

W. H. DAVIS TIRE PRESSURE CONTROLLING APPARATUS Filed April 9, 1958 -3Sheets-Shegt 3 Snucntor WHZ. TE H DAVIS (Ittomegs Patented May 2, 1939UNITED STATES PATENT OFFICE TIRE PRESSURE CONTROLLING APPARATUS Thisinvention relates to means on a motor vehicle for inflating thepneumatic tires thereof and for indicating the pressure therein at acentral point, as on the dash, or instrument board of the vehicle, andhas for an object the provision of apparatus of the character designatedwhich shall be reliable in operation and which may be tively rotatingparts is always available.

A still further object of my invention is to provide an air compressorfor inflating the tires together with a simplified drive for thecompressor from the vehicle engine.

A furtherobject of my invention is to provide apparatus of the characterdesignated which shall include means to inflate the tires, means toindicate the pressure in the tiresat some central point, such as on thevehicle dash, and means to equalize the pressure in the various sets oftires. Many efforts have heretofore been made to provide a means wherebythe operator of a motor vehicle could know at all times the pressurewithin the tires; and also to provide a means on the vehicle forinflating the tires, and for equalizing the pressure within the tires.So far as I am aware, none of these proposals has found its way intocommercial use. The principal difiiculty in the design of apparatus ofthe character herein described has been to provide a tight joint betweenrotating and non-rotating parts and also a joint which would reducefriction to a point where there is not excessive wear between suchrelatively movable parts.

This difliculty has been overcome, in accordance with-my invention, bythe provision of a pressure chamber in each hub cap having a flexible,or diaphragm wall, and by connecting this pressure chamber to itsassociated tire. A hollow axially extending stem connected to thediaphragm extends into an axial passage in a nonrotating part facing thediaphragm. The stem is packed against leakage and in addition, 00-operating seats in the passage and on the stem provide a pressure tightrotating joint. The mechanism being in, the hub cap, a supply oflubricant is available or may be made available for the relativelyrotating parts. Other features of my invention reside in a compressordriven means whereby a supply of lubricant for the relafrom the motor,an improved connection between the motor and the compressor, andimproved valve means for connecting the compressor to the variousvehicle tires and for equalizing the pressure in the various sets oftires.

These and other features are illustrated in the accompanying drawingsforming a part of this application, in which:

Fig. 1 is a diagrammatic view showing a general layout and typicalpiping arrangement employed with my invention;

Fig. 2 is a detail sectional view of an air compressor and its drive;

Fig. 3 is a view of a typical arrangement of gaugeson the instrumentpanel of the vehicle;

Fig. 4 is a sectional view showing the means connecting the pressurelines to the rear tire of the motor vehicle;

Fig. 5 is a view showing a method connecting the pressure lines to thefront tire of a motor vehicle;

Figs. 6 and 7 are views illustrating one means of equalizing thepressurein dual tires;

Fig. 8 is an outside view of a distributing and equalizing valveemployed with my invention;

Fig. 9 is a bottom plan view of the valve seat turned to the position asshown by the dotted lines of Fig. 8;

Fig, 10 is an enlarged sectional view taken along the line X-X of Fig.9;

Fig. 11 is a bottom plan view, somewhat reduced in size from Fig. 10,and partially in section, of the rotary valve member; and

Fig. 12 is a diagrammatic view showing a modifled means for inflatingand equalizing pressure within the tires.

Referring to the drawings, I show a motor vehicle comprising an enginel0, front pneumatic tired wheels H, and rear pneumatic tired wheels l2.A spare tire I3 may be carried, and mounted in any suitable place on thevehicle. Connected to a moving .part of the engine ill, in any suitablemanner, not shown, is a reciprocating arm M for driving an aircompressor IS. The air compressor delivers air under pressure through aconduit I! to a distributing valve l8, from which it may be directed, ina manner to be more particularly described hereinafter, through pipes l9and 2| to the front pneumatic tires ll; through pipes 22 and 23 to therear pneumatic tires I2; andthrough a pipe 24 to the spare tire I3. Thesaid pipes l9, 2|, 22, 23 and 24 are connected through pipes 26, 21, 28,29 and 3|, to a plurality of gauges 32, 33, 34, 35, and 3G, enclosedwithin a frame 31 mountedon the instrument panel 88'of the vehicle,where the pressure in each pneumatic tire may be observed at all times.It will be understood that dual type gauges may be used, if desired.

The air compressor i8 comprises a cylinder 88 enclosing a single actingpiston II which compresses on its down stroke and which is movedupwardlyfrom its downward position by means of a spring 42 resting against anabutment 48 in the cylinder wall and bearing against a plate 45 securedin any suitable manner to the piston rod 48, which latter extendsoutwardly through the upper end 48 of the cylinder. The upper end 48 ofthe cylinder is open to the atmosphere through ports 88 and 8|. Thepiston rod 48 is provided with a longitudinal passage 52 opening intothe upper end of the cylinder, at the lower end of which is a valve 53normally held on its seat by a small spring 54. As the piston 4| movesupwardly, air enters through the passage 52 and passes beneath thepiston past the valve 58. On its down stroke, the valve 58 is held onits seat by the spring 54 and the pressure of air ahead of the piston4|.- Compressed air is forced outwardly of the cylinder 38 past a checkvalve 58 normally held on its seat by means of a spring 51, and which isconnected to the discharge pipe il leading to the distributing valve l8.

Mounted above the cylinder 39 in suitable guideways 58, is a cylindricalmember 58 connected directly to the reciprocating arm l4 so that itreciprocates at all times when the engine is running. Disposed withinthe cylindrical member 59 is a piston 6|, and beneath the piston 8| is aspring 62 adapted normally to hold the piston in its uppermost position.A piston rod 88 extends downwardly through the bottom wall 84 of thecylindrical member 58, and is opposite the upper end of the piston rod48. Normally, the spring 82 holds the piston 6| in its uppermostposition, so that the piston rod 83 does not contact the upper end ofthe piston rod 48, and the compressor is not operated, the member 58merely reciprocating back and forth in its guide 58. If air underpressure be admitted to the upper end of the cylinder 58, it forces thepiston 6| downwardly and the piston rod 83 engages the piston rod 48.Then, as the cylinder member 58 moves downward, the piston ll is forceddownward, compressing air ahead of it, while the spring 42 causes thepiston rod 48 to move upwardly as the piston 8| moves upwardly. The areaof the piston 8| is made much greater than the area of the piston 4|,whereby a much lower pressure than the delivered pressure of thecompressor it, when admitted on top of the piston 8|, will cause thecompressor to operate. In the upper end of the cylinder 58 is a port 88to which is connected a pipe 81 leading to the equalizing anddistributing valve l8. Whenever it is desired to operate the pump, thedistributing valve i8 is turned to a position to be described in detailhereafter, to admit air under pressure through the pipe 81 and port 88to the cylinder 58. In order to allow for movement of the cylinder 88 Iinterpose a piece of flexible hose 88 between the cylinder and its pipe81.

Referring now to Figs. 4 and 5 of the drawings, I show the means bywhich the pipes i9, 2|, 2! and 28 are connected to the tires on thewheels of the vehicle. Fig. 4 illustrates the means preferably employedfor the rear wheels of the vehicles, and Fig. 5 the means employed forthe front wheels of the vehicle, though the means shown in Fig. 4 mightbe employed for both front and rear wheels, if desired.

Referring first to Fig. 4. in accordance with my invention I provide aspecial hub cap 88 which encloses a pressure chamber 89 formed by acylindrical cup-like member having a resilient diaphragm wall II. Thepressure chamber 88 is connected to its associated tire through a pipe12, so that the pressure within the tire is always within the pressurechamber 88. Mounted within the outer end II of the hub cap 88 is arelatively non-rotating member 14 having an axially extending passage 18therein. A ball bearing TI is provided between the member I4 and the hubcap I8, whereby the hub cap can rotate freely relative to thenon-rotating member 14. The member 14 is held firmly in place withrespect to the ball bearing race by means of a nut 18 secured onto theinner end thereof. It will be noted that the construction describedaffords a chamber 18 which may be packed with lubricant to insure freerelative movement between the member 14 and the hub cap.

Carried by each resilient diaphragm II is a hollow stem 8| which extendsinto the axial passage 18 of the member 14. The passage i6 is widened at82 to provide a shoulder 83 surrounding the outer end of the stem 8|. Asuitable packing 84, made of such material as rubber or an oil-insolublepacking material, such as synthetic rubber, surrounds the stem 8| andrests against the shoulder 83. Resting against the packing '83 andsurrounding the stem 8| is a seat member 86 provided with an invertedconical seat 81 thereon. The stem 8| at this point fits snugly withinthe inner end of the widened passage 82, and is provided with a seat 85coasting with the seat 81 to insure an air tight fit which preventsleakage from the tire through the stem and its cooperating non-rotatingmember 14. The tire associated with the hub cap 68 may be inflated froman outside source through the usual tire inflating valve 88, which ishere shown mounted on the non-rotating member and connects with thepassage 18. The pipe 23, as shown in Fig. 4, connects to the outer endof the member 14 and with the passage 16. It will be readily seen thatpressure within the pressure chamber 69 acting against the diaphragm 1|forces the seats 85 and 81 to remain in fluid tight contact. With hubcaps of large diameters, it may be necessary to reduce the size of thediaphragm 'II in order that the pressure on the seats shall not be toogreat.

In Fig. 5 I show an adaptation of the foregoing descrlbed device forconnection to the front wheel of the vehicle. In accordance with thismodification, a hub cap 88 is employed which encloses within its outerend a pressure chamber 8|. The pressure chamber 9| is provided with aflexible diaphragm wall II, as in the previously described modification,which wall ll carries an axially extending hollow stem 8|, which stem,however, in accordance with this invention, extends inwardly of the hubcap, rather than outwardly. A front axle is shown at 92 and is boredcentrally to form an axial passage 93 extending therethrough, and towhich the pipe 2| is connected at its inner end at 94. The passage 98 iswidened at 88 to provide for the installation of the packing 84 and seatmember 88, as in the previously described modification. The associatedtire is connected with the pressure chamber 8| through a pipe 91, andthe tire may be inflated from an outwide source through a valve 98 ofthe form usually associated 'with pneumatic tires.

With either form it will be seen that the seat portion of the stem 8| isheld on the seat 81 at all times by the resiliency of the diaphragm IIand by the pressure in the pressure chamber. It will also be seen thatthe construction is such that before any air can reach the seatportionsandbeyond, it must pass through the. tortuous passages defined by theenlarged portion of the stem, past the seats, again around the stem andpast the gasket 82. I have found that this arrangementeifectivelyprevents leakage. In the arrangement shown in Fig. 2 the stem8I is'immersed in the grease packing for the front wheel bearings sothat there is always present lubrication tor the stem 8|.

Where dual wheels are employed, as is the practice with large truckingvehicles, at the rear, the pipe I2 may be connected to an equalizingmember 99 having branch pipes I8I and I02 leading therefrom to (the dualtires I03 and I02. The member 99. may'enclose a piston I08 having apiston rod I'I secured thereon and held normally in mid position bymeans of springs I08 and I09 bearing against the piston and suitableabutments III and H2. Thepiston rod IN is somewhat shorter than thelength of the equalizing member 99 and carries on its opposed ends valvemembers H3 and H2, which are adapted to seat against seats H6 and Illconnected respectively to the pipes IOI and I 02. A restricted passageI05 extends through the piston I08. With the arrangement shown, thetires I03 and I02 may be inflated in unison to equal pressures. Should,however, one of the tires, in operation, blow out, or become suddenlydeflated from any cause, the greater pressure in the associated tirewill cause the piston I06 to move in the direction of the injured tire.and the valve H3 and H2, as the case may be, will then seat and preventrapid loss of pressure from the uninlured tire, the piston I08 assuminga position under such circumstances as to be past the pipe connection12. The restricted passage I05, however, will allow a slow leak ofpressure from the uninjured tire into the opposite end of the equalizer99, and when the pressure within the opposite end has built up tonearthat of the other end, the valve I I3 or I I2, as the case may be, willunseat momentarily, permitting a slight drop in pressure in theuniniured tire. This will give the operator of the vehicle suiflcienttime to note the inJury-to the tire and to stop before both tires becomeflat. I

Referring now to Figs. 8, to 11 inclusive, I will describe the detailconstruction of the distributingvalve I8. The" valve I8, as shown, is

, mounted on the instrument panel 38 and is provided with an operatinghandle I I8 with a pointer II9, which maybe set to suitably designatedoperating positions. The valve. I8 comprises a seat .I2I whichpreferably hascylindrical walls I forming a cup-like construction, andto which is connected the pipes I9, 2|, 22, 23, 22 and 6'! previouslydescribed. These pipes terminate, as shown in-the seat in Figs. 9 and10, in ports Illa, 2Ia, 22a, 23a, and 22a. The pipe, which leads to theport 65 in the top of the cylindrical mem-- her 59, divides and has twoconnections terminating in two ports 61a and 61b, as shown in Fig. 9.Additional connections to the seat may be made, as shown at I22, .incase there are a plurality of spare tires or a trailer. In thisinstance, the

75 connection I22 is shown plugged, as with a screw.

Cooperating with the valve seat I2I is a rotary valve I22 which iitswithin the cylindrical walls of the seat member III and which is held onits seat by means of a relatively heavy spring I22. An operating stemI28 extends outwardly through the cover I2'l of the valve assembly, andhas connected to it the operating handle H8. The valve I23 is providedwith three crossed passages I28, I29, and I3I, as shown in Fig. 11. Thepassages I 28 and I29 are provided with similarly arranged ports I22,I22, I22 and I38, which are adapted to register with corresponding portsin.

the valve seat Ila,v 2Ia, 22a, 23a, and 22a. The passage I28 is alsoprovided with a port I31 which is adapted, when the rotary valve isturned to the proper position, to connect with either of the ports 81::or GIb-in the valve seatas the valve is turned. The valve I22 isprovided with a port I28, which extends entirely through it, and whichis adapted, when the valve is turned to the off position, to connectwith port 61a and permit air from above the piston 6| to escape throughthe ports 86 and 61a to the atmosphere. The passage I3I in the rotaryvalve I23 is an equalizing passage, as will be hereinafter moreparticularly explained, and has positioned in it a small pipe I39 havinga flanged fluid tight hi: I and I22 at each end thereof with thepassage, whereby air pressure can only pass from end to end of thepassage, and its only connection with the valve seat is through portsI35 and I20 at opposite ends thereof (port I35 being broken away in Fig.11) and which may be turned to register with ports I9a, 2I a, 22a and23a. in the seat. Centrally of the valve I23 is a large port I23, whichis in register at all times with a large central port I22 in the valveseat, and to which the pipe I I from the compressor I8 is connected.

By reference to Fig- 8, it will be noticed that there is a dialsurrounding the distributing valve I8, and that the dial is marked withpositions off and "on to indicate the position of the rotary valve I23.When the pointer H9 is in the position shown in full lines in Fig. 8,pointing to ofif, the only ports in register between the valve and thevalve seat is port I38 of the valve which comes over port 81a in theseat. This permits air in the cylindrical member 59 to escape to theatmosphere through port-66, pipe 81, port 8112, and port I38. Wheneverthe pointer H9 is turned to the position onito the right of the position"off", the passages I28 and I29 are rotated until they are directly overports I9a, 2Ia, 22a, and 23a. Ports I32 and I36 in the valve registerwith the ports I9a, 2Ia, 22a, and 23a. One of the ports I32 registerswith port 22a. Port I31 registers with port 61b, which permits air fromthe tires to flow through the passages I28 and I29 through the port 61band pipe 61 to the cylinder 59, forcing the piston 68 downward for itsstem 83 to engage the stem 28 of the compressor piston 2|, therebyputting the compressor in operation. In this position all of the tireson the vehicle are being inflated at once. 0

When the pointer I I9 is turned to the left hand on position, the portI30 is in register with port 61!), causing the compressor to beoperated, as before described. In this position, the ports I9a and 2Ia,connected to the pipes IS'and 2| leading to the front tires areconnected through ports I20 and I35 (port I35 broken away in Fig. 11) toequalize the pressurein the front tires, while the pump is inflating therear and spare tires through pipe i1, port I, passage I20, and ports22a, Ila, and a.

It will thus be apparent that with the valve construction shown, byturning it to right hand on position, the compressor may be put inoperation and all the tires, including the spare tires, may be inflatedat one time; or if desired, the rear tire and spares may be connected tothe compressor and inflated at one time without inflating the fronttires by turning the pointer to the left "on position; or pressure inall the tires may be equalized, but respective pressures in the frontand rear, sets of tires may be a diiferent value;

and finally, the operation of the compressor may be stopped by turningthe pointer lll to the "oil" position.

Referring now to Fig. 12, I show a modifled form of means for supplyingpressure to the various tires. In accordance with this modification, Imay employ a compressor "I which is constantly operated by means of aconnection to the reciprocating arm ll, air being drawn in through acheck valve Iii and discharged through a similar check valve I52 andthrough a conduit I 83. A three wayvalve I may be turned so that thepump I50 discharges continuously to the atmosphere through a dischargeconduit I", or the three way valve I may be turned for the compressor todischarge through a conduit I51 into a manifold or reservoir I".Connected to the manifold I68 are a plurality of pipes lab, lib, 22b,28b and 24b, leading respectively to the front and rear tires and sparetire of the vehicle. Other I connections may be made as demanded. Eachof the pipes is controlled by a valve ill and is provided with a gaugeIii, which may be mounted as described for the gauges 32 to 36inclusive. To prevent excess pressure in the manifold or in the tires, asafety valve I" is provided in the discharge conduit III.

with the modiflcation just described, each of the tires may be inflatedindividually by opening the valve I" in its associated pipe. Also, thepressure in all the tires may be equalized by opening all the valves Illand allowing the tires to inflate to the pressure of the manifold asdetermined by the setting of the safety valve I".

From the foregoing description, the operation of my improved apparatuswill be clearly understood. It will be seen that I have provided a meanswhereby the tires on a motor vehicle in operation may be readilyinflated from the compressor actuated by the motor, and that there isprovided a practical, simple, and reliable pressure connection betweenthe relatively rotating parts which is not liable to leakage and which,being at all times in the presence of a lubricant, is well lubricatedand not liable to excessive wear. It will furthermore be apparent that Ihave devised an improved means for inflating and equalizing the pressurewithin the several tires of the vehicle and for controlling theoperation of the compressor.

While I have illustrated and described herein the preferred means forconstructing and operating my invention, it will be obvious to thoseskilled in the art that it is not so limited, but that t is susceptibleof various changes and modifications, without departing from the spiritthereof, and I desire, therefore, that only such limitations shall beplaced thereupon as are imposed by the prior art or as are specificallyset forth in the appended claims.

What I claim is:

1. In apparatus for controlling and indicating areas pressure in thetires of motor vehicles, a hub cap on each wheel of the motor vehicleand enclosing a pressure chamber, a flexible diaphragm comprising onetransverse wall of the pressure chamber, a hollow axially extending stemcarried centrally by the diaphragm and communicating with the chamber,means defining an axially extending non-rotating passage into which thestem fits, cooperating seat members on the stem and in the passage, acompressor on the vehicle, means to connect the compressor to thepassage, and means to connect the pressure chamber to its associatedtire.

'2. In apparatus for controlling and indicating pressure in the tires ofmotor vehicles, a hub cap on each wheel of the motor vehicle andenclosing a pressure chamber, a flexible diaphragm comprising onetransverse wall of.the pressure chamber, a hollow axially extending stemcarried centrally by the diaphragm, means defining an axially extendingnon-rotating passage into which the stem flts, cooperating seat memberson the stem and in the passage, means to lubricate the seat, acompressor on the vehicle, means to connect the compressor to thepassage, and means to connect the pressure chamber to its associatedtire.

3. In apparatus for controlling and indicating pressure in the tires ofmotor vehicles, a hub cap on each wheel of the motor vehicle andenclosing a pressure chamber, a flexible diaphragm comprising onetransverse wall of the pressure chamber, a hollow axially extending stemcarried centrally by the diaphragm and communicating with the chamber,means defining an axially exextending passages of the motor vehicle, acompressor on the vehicle and means to connect the compressor throughthe valve means to said axially extending passages.

4. In apparatus for controlling and indicating pressure in the tires ofmotor vehicles, a hub cap on each wheel of the motor vehicle andenclosing a pressure chamber, a flexible diaphragm comprising onetransverse wall of the pressure chamber, a hollow axially extendingstem. carried centrally by the diaphragm and communicating with thechamber, means defining an axially extending non-rotating passage intowhich the stem fits, said passage being enlarged toward the outer end toprovide a shoulder surrounding the hollow stem, a yieldable packinggasket resting on the shoulder and surrounding the stem, a conical seatmember resting on the gasket and surrounding the stem, 9. cooperatingseat member on the stem, a connection from each pressure chamber to itsassociated tire, pressure indicating means mounted on the vehicle, and aconnection from each non-rotating passage to thep ressure indicatingmeans.

5. In apparatus for controlling and indicating pressure in the tires ofmotor vehicles, a hub cap on each wheel of the motor vehicle andenclosing a pressure chamber, a flexible diaphragm comprising onetransverse wall of the pressure chamber, a hollow axially extending stemcarried centrally by the diaphragm and communicating with the chamber,means defining an axially extending non-rotating passage into which thestem flts, said passage being enlarged toward the outer end to provide ashoulder surrounding the hollow stem, 9. yieldable packing gasketresting on the shoulder and surrounding the stem, a

conical seat member resting on the gasket and surrounding the stem, acooperating seat memher on the stem, a connection from each pressurechamber to its associated tire, pressure indicating means mounted on thevehicle, a connection from each non-rotating passage to the pressureindicating means, a compressor mounted on the vehicle, and means toconnect the compressor to the non-rotating passage.

6. In a pneumatic tire pressure indicating device, a rotary hub capincluding a pressure chamber, a conduit connecting the pressure chamberto the tire, a flexible diaphragm forming the inner wall for thepressure chamber, a non-rotating part having a passage therein facingthe diaphragm, a hollow stem carried by the diaphragm and extending intothepassage to connect the pressure chamber to the latter, cooperatingseat members on the stem and the non-rotating part,

and means to indicate the pressure in the passage.

7. In a vehicle pneumatic tire pressure indicating apparatus, a vehiclewheel with a pneumatic tire mounted thereon, a hub cap for the wheel,means defining a pressure chamber in the hub cap, means connecting thepressure chamber to the tire, a flexible wall for the pressure chamberextending transversely of the hub cap, a hollow axially extending stemcarried by .the flexible wall, a relatively stationary part associatedwith the hub cap and having an axially extending passage therein, thehollow stem extending into the passage, cooperating seat members carriedby the stem and the stationary member and held in contact by thepressure in the pressure chamber, and pressure indicating apparatusconnected to the passage.

8. In a vehicle pneumatic tire pressure indicating apparatus, a vehiclewheel with a pneumatic tire mounted thereon, a hub cap for the wheel,means defining a pressure chamber in the hub cap, means connecting thepressure chamber to the tire, a flexible wall for the pressure extendingtransversely of the hub cap, a hollow axially extending stem carried bythe flexible wall, a relatively stationary part associated with the hubcap and having an axially extending passage therein,

the hollow stem extending into the passage, co-

operating seat members carried by the stem and the stationary member andheld in contact by the pressure in the pressure chamber, packing meansin the passage surrounding the hollow stem, a conical seat member in thepassage surrounding the hollow stem, a cooperating seat member on thestem, and pressure indicating apparatus connected to the passage. 7

9. Apparatus for indicating and controlling the pressure in pneumatictires of motor vehicles, comprising an air compressor, means to operatehe air compressor from the vehicle motor, distributing valve means incommunication with the compressor, a hub cap on each vehicle wheelincluding a pressure chamber connected to its assoei ciatedtire, adiaphragm wall for the pressure chamber extending transversely of thehubcap;

a hollow stem carried by the diaphragm and extending axially of the hubcap, a non-rotating part opposite the diaphragm having an axiallyextending passage therein, the hollow stem extending into the passageand rotating therein, an inverted conical seat member in the passagesurrounding the hollow stem, a cooperating seat member on the hollowstem adapted to rotate in fluid tight engagement on the first seatmember, and a connection from each of said passages to the distributingvalve means.

10. Apparatus for indicating and controlling the pressure in pneumatictires of motor vehicles comprising a reciprocating air compressor, apiston in the compressor, a reciprocating member driven by the engine ofthe motor vehicle pressure operated means for connecting thereciprocating member to the piston to operate the latter, a distributingvalve seat, a connection from the compressor to the seat, a hub cap oneach vehicle wheel including a pressure chamber connected to itsassociated tire, a diaphragm wall for the pressure chamber extendingtransversely of the hub cap, a hollow stem carried by the diaphragm andextending axially of the hub cap, a nonrotating part opposite thediaphragm having an axially extending passage therein, the hollow stemextending into the passage and rotating therein, means in the passage toprovide a fluid tight sliding iit around the stem, a connection a fromeach of said passages to the distributing valve seat, and a distributingvalve member provided with ports adapted to connect said passagesselectively through the valve seat to the compressor and' to each otherto inflate and equalize the pressure in the tires.

11. Apparatus for indicating and controlling the pressure in pneumatictires of motor vehicles comprising a reciprocating air compressor, apiston in the compressor, a reciprocating member driven by the engine ofthe motor vehicle, pressure operated means for connecting thereciprocating member to the piston to operate the latter, a distributingvalve seat, a connection from the compressor to the seat, a hub cap oneach vehicle wheel including a pressure chamber connected to itsassociated tire, a diaphragm wall for the pressure chamber extendingtransversely of the hub cap. a hollow stem carried by the diaphragm andextending axially of the hub cap, a non-rotating part opposite thediaphragm having an axially extending passage therein, the hollow stem.ex tending into the passage and rotating therein, means in the p e toprovide a fluid tight sliding fit around the stem, a connection fromeach of said passages to the distributing valve seat, a distributingvalve member provided with partsadapted to connect said passagesselectively through the valve seat to the compressor and to each otherto inflate and equalize the pressure in the tires, and means in saiddistributing valve member to connect said passages to the pressureoperated member to operate the pump.

WALTER H. DAVIS.

